Piston ring expander



iaienied June i, i936 PIS'EON RING iE i Charles N. Teetor, Hagerstown, ind., assior to The Perfect Circle Company,

Hagerstown,

Ind., a corporation of Indiana Application September 23, 1935, Serial No. 41,710

5 Claims.

My invention relates to piston ring expanders for internal combustion engines and the like, and it has to do more particularly with expanders of the type embodying a supporting band adapted 5 to be mounted in a piston ring groove and carrying a plurality of spring members arranged to expandingly engage the piston ring.

One of the objects of my invention is to provide an improved piston ring expander of the foregoing character which is simple in construction and which is highly eiiicient and durable in use.

Another object is to provide a piston ring exl pander wherein the spring members include lo spring arms adapted to cooperate with the supporting band in such a way that the spring arms flex uniformly throughout their length thereby insuring longer spring life and the desired ringexpanding action.

A more specific object is to provide a piston ring expander of the foregoing character wherein the supporting band is provided with springacting portions or sections behind the spring arms of the spring members, the arrangement being such that the supporting band augmenta the expanding action of the spring members and cooperates with the spring arms of the spring members to avoid centralization of flexing or bending strains and stresses at any one point therein.

Other objects and advantages will become-apparent as this description progresses and by reference to the drawing wherein,-

Figure 1 is a fragmentary perspective view of one form of expander embodying my invention;

Fig. 2 is a section taken substantially on line 2-2 of Fig. 1; and

Fig. 3 is a sectional plan view of a piston showing the expander in position behind a piston ring.

In the drawing, my invention is illustrated as applied to a piston I0 having a ring groove II. in which a piston ring I2 is mounted. An expander I3 embodying my invention is mounted in the ring groove II behind the ring I2.

The expander includes a supporting band It and a plurality of integral spring members I5 which are, preferably, cut and formed from a sheet of soft steel and thereafter heat-treated and tempered so that they become hard and resllient and have the characteristics of spring steel. The supporting band lIII is, preferably, of a width substantially equal to the width of the ring groove II, and it is of a length somewhat less than the circumference of the bottom of the ring groove.

In forming the band I I, it is given a wavy shape so that, when it is appliedto the piston ring groove, it, due to the wavy shape thereof. seats upon the bottom of the ring groove at spaced points I6 with the intervening wave sections Il spaced from the bottom of the ring groove and 5 providing spring-acting'sections inthe expander band.

The spring members I5 each include an intermediate portion lconnected to the upper edge of the supporting band It by a neck I9. It will be 10 seen from the drawing that the spring members are connected to the band I4 at ring groove contacting points I6 therein or between the springfacting sections I1 of the band. The intermediate portion of each spring member supports opl5 positely extending spring arms 20 which overlie the band I, and particularly the spring-acting sections I1 thereof. The outer ring contacting points 2l of the spring arms are slightly bowed or curved so as to avoid any tendency of the 20 sharp end-edges of the spring arms to dig into the inner surface of the piston ring.

In forming the expander, I, preferably, turn the spring member I5 over and upon the band in such a way that its intermediate portion I8 seats 25 against the band as best shown in Fig. 2. In this manner, and due to the bowed shape of the adjacent spring-acting sections I1 of the supporting band, the inner parts of spring arms 20 of the spring members I5 normally seat flush upon the 3U spring sections I1 of` the supporting band with the outer end parts thereof spaced from the band. The extent to which the spring arms 2U seat upon the band I4 depends, as will be appreciated, upon the amount of deflection of the spring arms in the 35 performance of the expanding action. It will be seen from the foregoing that by arranging the spring arms 20 in the manner described, the expanding action of the spring arms 2|) is augmented by the spring sections I'I of the band, and 40 thespring support afforded by the spring band sections I1 tends to distribute flexing `or' bending strains and stresses in such spring arms throughout the length of the latter. In other words,

tendency of the spring arms 20 to hinge or ex 4.5l

about any one point, as for example, at their' junction with the intermediate portion I8,is avoided; and, as the spring arms 20 are exed toward the supporting band I4, the spring support afforded by the band Il causes the exing or 50 vhinging points in the spring arnis to gradually move toward the outer ends of the latter through the gradually increasing resistance to flexing action in the spring arms by the spring sections I1 of the band. 65

It is believedthat the operation and advantages oi' my invention will be apparent from the yforegoing; and it is to be understood that, al- Ithough I have shown only one form of structure embodying my invention,`other changes in details and arrangement of parts may be resorted to without departing from the spirit and scope of my invention as defined by the claims that follow.

I claim: l

1. A piston ring expander comprising a spring metal supporting band, spring members carried by said band and each having an intermediate portion with spring arms extending therefrom in opposite directions and in overlying relation to said band, means connecting the intermediate portions of said spring members to said band. and said band being bowed outwardly beneath said spring arms providing spring sections in said band upon which said spring arms seat.

2. A piston ring expander comprising a spring metal supporting band having uniformly spaced bowed portions therein throughout its length, spring members each having an intermediate portion with spring arms extending in opposite directions therefrom, means for connecting the intermediate portion of each said spring member to said band with said spring arms each overlying and seated upon a bowed portion of said band with the outer ends of said spring arms i'ree and spaced from said band, said band being adapted to seat upon the bottom of a ring groove with its bowed portions projecting toward a pistonV ring inthe groove to cooperate with said spring arms in expanding the ring.

3.A piston ring'expander comprisinga wavy spring metal band in which the several waves are of substantially uniform depth providing a 5 plurality of spring sections in said band, and spring members each having an intermediate portion carried by said band between adjacent of said spring sections and also having spring arms carried by said intermediate portion and overlying the outer face of said band, said spring arms being so constructed and arranged that they each seat in part upon said band spring sections with their end portions free and spaced from Said band.

4. A piston ring expander comprising a supporting band formed of spring metal and having spaced spring-acting portions formed therein. spring members having intermediate portions with spring arms projecting in opposite direc- 29 tions therefrom, and means connecting the intermediate portion of each said spring member to said band between two of said spring-acting portions with said spring arms overlying the outer face of said band and seated for part way of 25 their length upon the respective adjacent springacting band portions.

5. A piston ring expander comprising a spring metal supporting band and spring arms carried by said band in overlying relation thereto. said 30 band being bowed outwardly beneath said spring arms to provide spring sections in said band upon which said spring arms seat.

CHARLES N. TEETOR. 

